Iron core for magnetic apparatus



June 3, 1930. K. SCHMIDT ET AL IRON CORE FOR MAGNETIC APPARATUS Filed Jan. 9, 1928 fiar/ aSc/vmidt $5 Vl/ter/z'a/menzann "lien 0P6 Om Patented June-"3,1930

UNITED STATES PATENT OFFICE KARL SCHKIDT, OF BEBLIN-LICHTENRADE, AND WALTER HAHNEKANN, 01' BERLIN- IABHINFELDE, GEBKANY, ASSIGNORS TO C. LORENZ, flan u:

BERLINQIEKPEITEOF, GERMANY IRON CORE FOR MAGNETIC APPARATUS Application filed January 9, 1928, Serial No. 245,611, and in Germany September 14, 1986.

It is well known'that in laminated iron cores for alternating current magnetization, with paper insulated punchings, the heat conductivity across the punchings is about 5 one-hundredth part of the heat conductivity along the punchings. This ratio is even higher when thin punchings are used such as, for instance, high frequency punchings.

This can be easily understood because in the direction across the punchings there is an insulating layer between the two punchings which is a poor conductor of heat.

It necessarily follows that the surface consisting of the exposed edges of the lamina- 16 tions would radiate heat many times faster, than any of the other surfaces that would consist merely of a fiat side of one lamination referred to in .this application as the flat surface of the core. For the purposes of 20 this invention such an exposed edge surface will be defined as the cross sectional cooling surface throughoutthis description and in the claim following.

According to this invention the conduction of heat away from the core is improved by increasing the above defined cross sectional cooling surface to a multiple in respect to the flat surface by the simple expedient of making the extension of the cross sectional surface of the laminations across the punchings a multi le of the extension along the \mc his has the effect of increasmg the very eliective cross-sectional cooling surface relative to the ineffective flat surface, whereby the resulting cooling action of the core is considerably increased over large surfaces of the core instead of over small surfaces of the core. 4

The invention is made clearer by the following detailed description taken with reference to the accompanying drawing in which Figure 1 is a cross-sectional view of an im roved form of iron 'core in accordance wi our invention.

Figure 2 is a ores-sectional view taken at right angles to Figure 1 through one of the core sections.

An especially suitable form of embodiment according to the inventive idea is had by rollcase is the outer cylindrical surface of the transformer windings. In this manner too the cross sectional surface of the core is made a multiple of the fiat surface which in this rings. F ig. 1 shows discs or R, R ctc., mounted on an insulat' cylinder Z, through the center of which the transformer windings W are placed as shown. 2 is a cross section taken at right angles to the section of Fig. 1. Fig. 2 also shows the spiral arrangement of the lamination in the cores R to R This arrangement is quite suitable for high frequency transformers and permits the use of iron in high frequency transmission circuits. Despite of the small over all dimensions of the high frequency transformer cores used in transmitters, it has been impossible to remove the generated heat which is proportionately no larger than with usual apparatus. By the use of iron core in the described manner, the heat is removed by air blast instead of oil cooling so continuously that the iron will not assume any dengerous rise in temperature.

- The coresshown in Figs. 1 and 2 the big advantage of increased 000 ability. This is especially important wi iron cores that handle high frequen magnetization such as for frequency tran irmers ironcore choke modulators and the like, since, in this case, the use of iron leads very often to a condition where the losses in the form of heat cannot be carried away from the iron, even though the mean winding turn and the copper losses related to it are small compared to the iron losses.

Having described our invention, what we believe to be new and desire to secure and protect by Letters Patent of the United States A core for high frequency electromagnetic apparatus comprising a group of core sections arranged in axial alineinent, said sections being spaced from each other to provide passages for the free passage of a cooling medium between said sections, each of said sections consisting of a narrow strip of iron spirally wound to form a cylinder having a radial dimension which is a large multiple of the width of the strip, the width dimension of each of said strips being perpendicular to said passages whereby said passages intercept the paths of maximum conduction of heat developed in said corc sections. 4

In testimony whereof we have afiixed our signatures.

WALTER HAHNEMANN.

SCHMIDT. 

